The present invention relates generally to the field of micro-electronics that include fin formations (for example, FINFETs (“Fin field effect transistors”)).
A FINFET is a nonplanar, double-gate transistor built on an SOI (silicon on insulator) substrate. The distinguishing characteristic of the FINFET is that the conducting channel passes orthogonally through an elongated, relatively high, relatively thin, fin structure. Typically, the fin structure is made of silicon, although Silicon-Germanium (SiGe) fins are also known. This fin structure forms the body of the device. The thickness of the fin (measured in the direction from source to drain) determines the effective “channel length” of the device. FINFETs can provide better electrical control over the channel, reduce the leakage current and avoid certain unfavorable short-channel effects associated with non-FINFET devices. As used herein, the term “FINFET” means any transistor device with a fin structure located between its source(s) and drain(s), regardless of the number of gates.
It is currently conventional to form SiGe fins by growing a blanket layer (or block) of SiGe and then cutting away material to form the fin structures by SIT (sidewall image transfer).